Alpine's V Series is a nice series of mid-grade amplifiers. They aren't high end, but they price is isn't "high end" either. They are efficient and work well with vehicles that don't exactly have a lot of extra amps available for powering amplifiers.
The only downside I've found is that the EQ functions are rather limited. You get controls for center frequency, crossover point, and bass boost.
Overall, I'm very happy with the M500. As long as you're not looking to power a massive, inefficient subwoofer, it should give you a very smooth, musical sound.
Available on http://www.caraudiosystemz.co.uk